Loom shuttle boxing



Jan. 7, 1958' v w. A. SHERWOOIS 2,818,884

LOOM SHUTTLE BOXING 4 Sheets-Sheet 1 Filed Aug. 11, 1954 SMEKWOOD INVENTOR.

Marga I? Jan. '7, 1958 Filed Aug. 11, 1954 w. A. SHERWOOD 2,818,884

LOOM SHUTTLE BOXING 4 Sheets-Sheet 4 INVENTOR.

31407716 ROS/770 United States Patent LooM SHUTTLE BOXING Walter A. Sherwood, Hempstead, N. Y. Application August 1-1, 1954, Serial No. 449,103 11 Claims. (Ci. 139 186 This invention relates to the boxing of shuttles in looms.

In a. conventional loom the shuttle is thrown back and forth by picker sticks synchronized with the operation of the loom generally, being caught and stopped at the end of each motion between a stationary and movable binder and by the picker. The binders are generally leather lined or surfaced and the movable binder is spring urged against the shuttle so as to maintain, at least roughly, sufiicient frictional force to do the major part of the work involved in stopping the shuttle. The picker stick absorbs the balance of the kinetic energy and brings the shuttle to a stop, being yieldingly held by check straps and lug straps, generally made of leather. The opera ti'on is unsatisfactory in a number of respects, as the control over the deceleration and stopping of the shuttle is not accurate and it is found that improper boxing of the shuttle is a frequent cause of bang-offs or loom stoppages, as, for example, where the shuttle may rebound from the picker. Wear and replacement costs of the binder surfacing, the check straps and the shuttles are also considerable. At best the action is not-smooth, predictable and regulated, but is erratic. For example, examination of the wear of the; movable binder surface indicates that a rebound of the binder after the first impact of the shuttle is characteristic.

A variety of proposals to' improve the conventional shuttle boxing have been made buthave not had any significant success. Thus, shock absorption has'been provided in connection with the picker stick in the hope of absorbing theshuttle energy more smoothly and predictably, and expedients have also been proposed for modifying the spring pressure on the movable binder, as, for example, by releasing it when the shuttle has been stopped, on modifying it by means of linkage connections and hydraulic check devices. The inherent characte'ristics of the shuttle boxing mechanism have not, however, been improved sufliciently to justify adoption of any of these expedients.

The general object of the present invention is to provide an improved shuttle boxing mechanism, permitting accurately regulated and smooth deceleration and stopping of the shuttle and in so doing eliminating the defects above mentioned. It has been found that'by regulating the binder pressure against the shuttle hydraulically a very great improvement can be effected, and to a point where substantially the entire deceleration maybe accomplished by the binder friction, and the precise stopping point of the shuttle may" also be determined with complete accuracy; It has also been found possible to eliminate the check straps, to reduce the need for adjustmems practically. to the vanishing point and to reduce the power consumptionand wear on binders, pickers and shuttles in a very marked degree. 7

A shuttle boxing mechanism embodying the invention in'a preferred form'will now 'be described 'with reference to the accompanying drawings and the' features forming the invention will then be pointed out in the'appended claims. i

"ice

In the drawing Fig. l is a perspective, showing a loom in phantom hues and the shuttle boxing arrangement in solid lines. Fig. 2 is a plan view on an enlarged scale of the shuttle boxing mechanism and is taken in the direction of the arrows 22. Fig. 3 is a section further enlarged, on the line 'of Fig. 2. Figs. 4, 5 and 6 are further enlarged sections of rnodified forms of hydraulic device which may be substituted for the device of Fig. 3. Figs. 7 and 8 are graphs or diagrams illustrating the action of the device. V p

Referring first to Fig. 1, showing the shuttle boxing mechanism 10 as applied to a loom, it will be understood that this mechanism, together with the picker stickll and operating mechanism therefor, indicated generally at 12 are duplicated at the far end of the 100111. It maybe noted that a picker stick bumper 13 may be desirable to stop the picker stick, in view of the elimination of the usual check straps. Since the loom structure and operation are, in general, well known and their details form no part of the present invention, the loom will not be further described. n

In Fig. 2 there is shown a fixed binder 20, with leather covering 21, movable binder 22 with leather covering 23', and pivot 24 for the movable binder. There is indicated in phantom, at 25, the lay, to which the fixed binder is attached, and a bracket 26 also attached to the lay and mounting the movable binder pivot 24. Angle 27 attached to the lay and strap 28 serve to supportthe hydraulic check or buffer, indicated generally by reference numeral 30, in cooperating position with respect to the movable binder 22. The picker is indicated at 31 and a shuttle in boxed position, at 32. Fixed guide 33 at entrance of the box guides the shuttle prior to its contact with movable binder 22 and also serves as a stop," limiting inward movement of the movable binder when the box is empty. Apart from the buffer and apart from the omission of parts such as the check straps and movable binder spring; the construction may be entirely conventional.

The check 30 comprises a cylinder 35 in which there reciprocates a piston 36; provided with a piston rod 37 to which is attached a head 38 for contacting the binder 22'. Head 38 may be removably secured to rod 37 by a" screw 39 and fittedwith a fiber wear block or cushion 40. The cylinder head 41 may be screwed into the" cylinder 35, as shown, and sealed in any convenient way.

Between the cylinder head 41 and piston rod head 38 and in sealed relation to them, is a sylphon or bellows 42,

the, interior of which serves as a hydraulic liquid reser voir, and which communicates with the cylinder low pressure space 43 through openings 44 in the cylinder head.

The buffer is provided with what is, in effect, a metering pin byforming the piston 36 with a groove coopending with a tapered lug 51 fixed to the cylinder, so that the area for flow between low pressure space 43 and working or high-pressure space 52 is determined by the variable flow area around lug 51 within the groove 50. The flow area for any given position of the piston is accurately determined by selecting the configuration of lug 51 and groove 50. Asmall bore passage 53 through the piston 36 is also provided, for purposes ex plained below.

The sylphon l2 may be built with sufiicient spring'to' return the buffer to the position of Fig. 3, after a working stroke, or a separate return spring may be provided, either internally or externally of the buffer. In either event, the spring will be relatively weak, aspointed out' more fully below. The preferred hydraulic fluid is a" hydraulic oil, and the oil may fill space 52' and about half fill space 43 andth'e sylphon 42 in the position of the figures.

As is apparent, the movement of the buffer piston 36 will depend on the shuttle movement and the con-' figuration of the shuttle-contacting surfaces of the binders. By simple adjustments of the contour of the lug 51, desired hydraulic resistance variation may be obtained to suit desired curvature of the binders. However, there is no significant advantage to binders deviating markedly from the usual nearly fiat surface and it will be assumed that straight or flat binders, such as illustrated are used. Under such conditions the buffer piston displacement will be, theoretically, a tangent function of shuttle distance from point of entry and, in actuality, so close to directly proportional that linear relationship between these displacements or movements may be assumed with negligible error.

The point of application of force between binder 22 and buffer 30 being at fixed distance from the pivot 24, it will be apparent that the mechanical advantage of buffer over shuttle will vary with distance of the point of contact of the shuttle with the binder from the pivot point 24. In the construction shown, the advantage ratio is approximately unity at time ofentry of the shuttle and increases to about four or five-to-one as the shuttle moves in and reaches its final position, as shown in Fig. 2. The ratio between the velocity of piston 36 and the velocity of movement of the shuttle increases accordingly. However, the piston movement and ratio of movement corresponding to each shuttle movement and speed are determined by the and may be laid out graphically, permitting determina tion of metering lug or pin profile without difiiculty.

In an ideal shuttle boxing action, a constant frictional deceleration is preferred, as indicated in Fig. 8 giving a linear decrease in velocity from point of entry (left) to final stopping position (right). At the extreme end of the movement, the orifice may close to increase the deceleration markedly, and the contact with the picker stick may absorb, with or without some rebound, such small residual energy as is left thus bringing the shuttle to a quick stop if there should be any tendency to overshoot the selected stopping point.

Under these conditions the fiow orifice through or around the piston may decrease in a practically linear manner, as indicated in Fig. 7, giving the desired acceleration and velocity curves of Fig. 8.

In a reasonably typical loom operation there may be about 180 picks per minute, which means about twothirds of a second elapsed time during a complete cycle of shuttle movement. Starting, for example, at the time of entry of a shuttle, or first contact with the binders,

geometry of the parts there will first of all be a certain time required to stop the shuttle and bring it to rest. This may be about .044 second. Thereafter there will be a delay before the picker stick is actuated to throw the shuttle, which may involve about .166 second. The flight of the shuttle may require about 0.1 second in each direction. It will be observed that in each complete cycle of shuttle movements, the time required to bring the shuttle to rest plus the time lapse before the shuttle is thrown by the picker may amount to about .012 of a second or slightly more, leaving about 0.4 of a second for the return movement of the buffer in preparation for again engaging the shuttle. This is about ten times as great a period of time, as the time required for boxing the shuttle, and permits the use of a relatively weak return spring for the buffer.

Typically the return spring force may be made sufficiently small so that it is less than five percent, and typically only about two percent, of the hydraulic resistance force produced by the movement of the binder as the shuttle moves in. The action is therefore substantially a pure dead hydraulic action and is Without sensible recoil. No difliculty is experienced in stopping the shuttle with an accuracy of one-sixteenth of an inch, which, in View of the general operating characteristics of the loom, is as accurate as could be desired.

The energy absorption by friction against the binders may be practically complete, leaving two or three percent, or even less of the initial kinetic energy of the shuttle to be absorbed by the picker. Thus in a loom where the shuttle kinetic energy in flight is about 40 foot pounds, it was found that a conventional boxing arrangement resulted in the absorption of only about 85% of the energy of the shuttle by binder friction leaving about 8 foot pounds to be absorbed by the picker. With the system of the present invention it was found that 98 and 99 percent of the shuttle energy could be readily and controllably absorbed by binder friction, leaving only about one-half foot pound for absorption of the picker. Even this energy absorption by the picker is not at all necessary for the boxing of the shuttle. but is merely an incident to the picker stick movement, which does not include a positive return for the picker stick. Striking bumper 13, after throwing the shuttle, the picker stick will rebound against the closed end 34 of the box and come to rest in a somewhatvariable location. "It is found, however, that this has no essential effect on the operation, as the stopping point of the shuttle with the picker entirely removed and with the picker: engaged by the shuttle two or three inches within the box will not differ by more than one-sixteenth inch, which is negligible.

It is found that the hydraulic cylinder shows little or no heating in operation and it may be noted that energy absorption by this cylinder is merely incidental. With standard components such as the binders, it is found that of the total kinetic energy in the shuttle only a fraction (typically 10 to 20 percent) is absorbed by the buffer cylinder. The buffer thus functions, not as a typical shock absorber, but as a regulated pressure applying device for the movable binder, and analysis shows that by increased precision in the manufacture of the parts the energy absorption of the hydraulic cylinder could be reduced (theoretically) as far as desired (typically 10 to 20 percent).

While the amount of energy absorbed by the hydraulic cylinder is not a matter of any great importance in itself, the fact that energy absorption by the cylinder is not inherently involved in the principle of operation is of considerable importance. The fact that this feature can be substantially ignored simplifies the design and makes the operation self-compensating instead of critical, as might otherwise be the case.

It has been found that variations of shuttle velocity of the order of twenty-five percent above or below a given value are compensated without perceptable variation in shuttle stopping point. A major reason for this will be apparent when it is considered that, at any given instant, the hydraulic cylinder resistance is a function of both shuttle position and shuttle velocity, so that a shuttle entering at higher (or lower) velocity will .be more rapidly (or slowly) checked, the deceleration being at first greater (or less) than the normal fixed value of Fig. 8 and then returning asymptotically or exponentially to the flat curve. The pressure-drop flow characteristic of the flow orifice around piston 36 being typically of a type in which the pressure-drop is proportioned to the square or similar power of the flow velocity, the reaction to any departure of velocity from the designed curve is sensitive and com pensating.

While the coefficient of friction and variation thereof with velocity of the leather binder surfaces is difiicult to measure with accuracy, it is known that variation of this coeflicient due to moisture or dryness of the leather can be sufficient to cause bang-offs due to improper boxing in conventional looms. In an experimental operation where variation exceeded anything to be expected in a mill, and was estimated as being as much as fifty percent in the coefficient of friction, no appreciable variation in the stopping point of the shuttle was detected. The effect here is clearly to introduce a displacement and curvature in the initial portions of the deceleration and velocity curves; which, through the compensating action referred toabove, are quickly ironed out.

Operation in a mill in parallel with conventional looms has indicated an absence of bang-offs due to improper boxing, as compared with the usual frequent bang-offs for this reason with conventional shuttle boxing equipment. It is therefore believed, on the basis of results which, While still preliminary, are based on suflicient experience to appear reliable, that a theoretically and practically correct shuttle boxing system has been arrived at. It thus appears that a problem which has been widely recognized as one of the two or three major problems of loom operation has been solved or eliminated in a completely satisfactory manner. The same experimental operations have indicated that need for adjustment during a shift to compensate for wear and other changes in operating conditions, which has been continual, has practically been eliminated.

The initial installation adjustment of the mechanism ordinarily involves merely the placement of the hydraulic cylinder with piston head top against the movable binder 22 (binder springs removed), with a shuttle in the box, the cylinder being compressed to the designed extent and tightening up the clamp strap 28. Further adjustments will be required only at very infrequent intervals.

The cylinder return stroke can be accomplished without check valves or other special provision to facilitate return by a very weak spring, the return flow occurring in this case through the working orifice between lug 51 and groove 50. It appears that even under these conditions an ideal shuttle boxing action is obtained, the spring pressure perhaps serving a (theoretically) useful purpose in canceling loss of hydraulic resistance pressure due to leakage in the shuttle stopping position of the cylinder. However, any such spring pressure is disadvantageous in opposing the throwing out of the shuttle by the picker at the next pick. An elongated fine bore 53 in parallel with the working orifice and having the characteristics of a viscous resistance may be used to permit use of a weaker return spring, as a passage of this character may function to permit appreciable flow at very slow (return) speeds while practically blocking any flow at higher (working) speeds.

As the parts wear it will ultimately become necessary to reposition the cylinder 39 to maintain proper relation of orifice area (Fig. 7) to shuttle position and primarily to shuttle stopping position. Fig. 4 shows a structure incorporating an automatic compensation for these wear effects, and also utilizing a different sealing system. In

this case, the buffer head 33 is carried, as before, by a piston 36' in the cylinder 35, which however is hollowwalled to provide a fluid reservoir 35". The cylinder head 54 encloses a spring pressed seal 55 so that only slight leakage passes out into the sealing bellows 56. The bellows 56 take the form of a rubber or synthetic rubber sleeve and a separate return spring 57 is provided. The metering pin 58 is carried on a piston 59 in the cylinder 35 and a further guide piston 60 in a central bore in the piston. A spring 6?. serves to control the metering pin position. During any given stroke the metering pin position is fixed, and before, but a gradual creep is permitted by reason of leakage around piston 59 (solidly backed with oil). Thus, if the terminal pressure produced is materially above or below designed value, the metering pin automatically adjusts to reestablish the desired relation between flow orifice and shuttle position.

Fig. 5 illustrates a structure using sealing arrangements like those of Fig. 4, but a fixed metering pin 63 and foot valve 64 for flow of oil on the return stroke.

Fig. 6 shows still a further form of cylinder, in which a floating metering pin 65 is used, the pin being carried by a dash pot piston 66 equipped with return spring 67 and controlled by a dash pot orifice 68. Following each operation, spring 67 returns the metering pin 65 to the open position of the figure. As the shuttle enters the box, the working space pressure developed drives the pin 65 into the piston, gradually closing the flow orifice, at a rate depending upon the pressure and upon the pressure developed in dash pot orifice 68. Since the operating conditions of Fig. 8 determine a time-displacement curve (Fig. 7) selection of suitable time constantly for the metering pin dash pot of Fig. 6 will produce the same orifice-displacement curve of Fig. 7 and equivalent action to that already described.

While a particularly preferred form of mounting for the hydraulic check has been shown, in which the check is attached to the lay and abuts against the movable binder, other forms of mounting may be used, where conditions make this desirable. For example, the check may in certain cases be mounted on the binder and abut against a part fixed to the lay, or the buifer may be slidably supported and abut against the binder and an element fixed with respect to the lay. Still further, joint. or pivotal connections may be used at the ends of the check, where preferred. This last expedient will, of course, be appropriate where an external return spring is employed.

In general the movable binder spring is eliminated along with the check straps, and it may be unnecessary to alter the protector spring. However, in some looms the protector spring supplies a very considerable part of the total spring pressure applied to the movable binder and in such cases it may be necessary to weaken the action of this spring, for best results. As will be apparent, the protector spring may itself serve as the return spring for the movable binder and hydraulic check and in this case a reduction in overall spring pressure on the binder may be effected by eliminating internal return springs in the checks. While it is preferred to mount the check directly between lay and movable binder, as described above, and there is ordinarily no advantage in mounting it otherwise, the check may operate through a bell crank or other linkage or gear connections, where conditions make this desirable, and may be associated with existing mechanisms, such as the arms and shafting which, operate the protectors.

In the preferred construction disclosed, a check having a linear reciprocating movement, as opposed to a rotary movement, is used and this check is mounted horizontally since this is the simplest possible mounting in view of the pivoting of the movable binder about a vertical axis. The sylphon (Fig. 3) or flexible rubber (Figs. 4 to 6) seals greatly simplify the construction in that the space within the seal member may function as a reservoir for the hydraulic fluid (Fig. 3) or may be available to catch and hold any leakage of oil (Figs. 4 to 6) which may get past a separate seal around the piston rod. Any danger of leakage of oil and consequent possible spoilage of the fabric is thus eliminated, even though the low pressure space around the piston rod may, at times, contain oil above the piston rod level.

What is claimed is:

1. Loom shuttle boxing mechanism comprising a movable binder, a hydraulic check opposing movement of the binder by a shuttle and variable orifice means for regulating the resistance of the check as a shuttle moves into the box.

2. Loom shuttle boxing mechanism comprising a movable binder, a hydraulic check opposing movement of the binder by a shuttle and variable orifice means for regulating the resistance of the check as a shuttle moves into the box, whereby a substantially constant shuttle deceleration is obtained.

3. Loom shuttle boxing mechanism comprising a movable binder pivotally carried by the lay, a hydraulic check fixed to the lay and abutting against the binder for opposing movement of the binder by a shuttle, and variable orifices means for increasing the resistance of the check as a shuttle moves into the box.

. 4. Loom. shuttle boxing mechanism according to claim 3 in which the means fixing the cylinder to the lay comprises adjustable means for regulating the extent of compression of the check corresponding to a predetermined position of the binder.

5. Loom shuttle boxing mechanism comprising a movable binder, a hydraulic check opposing movement of the binder by a shuttle and having variable orifice means for increasing the hydraulic resistance as a shuttle moves in the box, and resilient return means for the cylinder and hinder, the force exerted by the said resilient return means constituting less than five percent of the hydraulic resistance force developed by the hydraulic check.

.6. Loom shuttle boxing mechanism according to claim 5, in which the force exerted by the said resilient return means is substantially that required to return the movable binder in the time lapse between throwing and re turn of a shuttle.

7. Loom shuttle boxing mechanism comprising a movable binder,

a linear reciprocating hydraulic check op- ...0 posing movement of the binder by a shuttle, the check comprising cooperating piston and cylinder elements and including a piston rod reciprocal in and extending out of a cylinder head, and means for preventing escape of hy- 8 draulic fluid, comprising a flexible sealing element connected to the cylinder and to a. piston rodexternally thereof to form an enclosed space surrounding the piston rod.

8. Loom shuttle boxing mechanism according to claim 7, comprising means mounting check horizontally.

9. Loom shuttle boxing mechanism according to claim 8.- in which the cylinder head has openings for flow of hydraulic fluid, whereby said enclosed space serves as a hydraulic fluid reservoir.

10. Loom shuttle boxing mechanism according to claim 7 in which the said flexible sealing element is a sylphon bellows.

11. Loom shuttle boxing mechanism according to claim 7 in which said flexible sealing element is a sheet of flexible material.

References Cited in the file of this patent-- I UNITED STATES PATENTS 

